1. Field of the Invention
This invention relates to a vehicle brake booster, and more particularly to a hydraulic type vehicle brake booster which can be installed at a desired point of a pipe which connecting a master cylinder to a wheel cylinder.
2. Description of the Related Art
A hydraulic vehicle brake booster system has been well known in the conventional art, as a mechanism for increasing the force of depression applied to a brake pedal.
The conventional vehicle brake booster system comprises; an accumulator which stores a brake fluid discharged from a pump; a hydraulic booster which performs a boosting action with the hydraulic pressure supplied from the accumulator in response to an operation of the brake pedal; a master cylinder to which the pressurized fluid which has been boosted by the hydraulic booster is transmitted; and a wheel cylinder (wheel cylinders) to which the hydraulic pressure of the master cylinder is transmitted to perform a braking action. An electro-magnetic control valve which is opened and closed by an operation of the ignition switch, is provided between the accumulator and the hydraulic booster. That is, when the ignition switch is turned on, the electromagnetic control valve is opened so that the accumulator is communicated with the hydraulic booster; and when the ignition switched is turned off, the electromagnetic control valve is closed so that the accumulator is disconnected from the hydraulic booster. Hence, even in the case where the vehicle is held stopped for a long period of time although internal leakage occurs with the control valve provided in the hydraulic booster, the hydraulic pressure of the accumulator will never drop, being held at a predetermined value. That is, the risk is eliminated that the hydraulic booster cannot perform the boosting action.
However, presently used vehicle brake booster system including the above-described hydraulic vehicle brake booster suffer from the following risk: That is, the vehicle brake booster is coupled directly to the master cylinder, and therefore the distance between the vehicle brake booster mounting surface and the end of the master cylinder is long. Hence, the vehicle brake booster is low in the degree of freedom of installation.